Textile fabrics provided with fillers, in particular fillers having heat-regulating properties, are known.
EP-A-178 372 discloses a drapable microporous multilayer nonwoven fabric for medical applications. The middle layer is composed of microfibers, and is covered on both sides with nonwoven fabrics. The individual layers are joined by use of a binder paste, a paraffin emulsion, for example, imprinted in a pattern.
EP-A-190 788 describes nonwovens which contain microspheres, preferably foamed, which are arranged in patterns and which may be used as reinforcement materials for plastics.
U.S. Pat. No. 5,366,801 or EP-A-611 330 describe the coating of a woven fabric with a binder and microcapsules distributed therein which contain a phase change material.
A nonwoven fabric having temperature-regulating properties is known from WO-A-02/12607. In one embodiment described therein, the nonwoven fabric is impregnated with a binder containing a dispersed microencapsulated phase change material. The material which imparts heat-regulating properties is distributed throughout the interior of the nonwoven fabric. In addition to embodiments in which the entire inner volume is filled with this material, variants are described in which the material is present only at the intersection points of the fibers, and the interstices are filled with air. However, in this cited embodiment the entire nonwoven fabric is impregnated with the material. This is achieved by saturating the provided nonwoven fabric with the binder. Nonwoven fabrics, i.e., mechanically stabilized/bonded materials, are used as starting materials.
WO-A-02/59414 describes a coated material having temperature-regulating properties and improved flexibility and air permeability. The coated material is composed of a substrate which is provided on a portion of its surface with binder dots or with layers of binders containing temperature-regulating materials. The binders may be applied to the surface, or may penetrate into the interior of the substrate and partially or completely permeate same. In any case, a portion of the surface is not impregnated with binder. Various coated substrates such as woven fabrics, nonwoven fabrics, films, foams, and papers are described.
Substrates having improved temperature-regulating properties are also known from WO-A-02/95314. According to the cited document, polymer dispersions containing phase change materials are applied in a napped pattern to a textile surface by screen printing. In addition to metal foils and textile surfaces, nonwoven fabrics, i.e. mechanically stabilized materials/bonded fibrous webs, are mentioned as possible substrates.
The substrates used heretofore in the prior art with regard to textile surfaces are structures which after production are stabilized (bonded, consolidated) to allow ease of handling. Thus, for example, nonwoven fabrics are manufactured by providing a fibrous web with a surface which is still mechanically unstable (“fleece formation”), then performing nonwoven bonding (see, for example, Vliesstoffe [Nonwoven Fabrics], edited by W. Albrecht, H. Fuchs, and W. Kittelmann, Wiley-VCH (2000), Part II, Manufacturing Methods for Nonwoven Fabrics, Chapter 6, Nonwoven Bonding). Typical processes for nonwoven bonding include chemical methods, such as application of a binder, or physical methods (mechanical and/or thermal methods), such as needling, interlacing, treatment with heated air, or calendering. These processes directly follow the nonwoven fabric formation process in order to convert the mechanically very unstable fibrous web to a manipulable form.
In the sense of the present description, “nonwoven fabrics” are understood to mean processed layers, fleeces, or fibrous webs composed of directionally or randomly oriented fibers which are bonded by friction and/or cohesion and/or adhesion (as defined in ISO 9092 or EN 29 092).
Attempts have also been made to apply the binder by screen printing directly after formation of the nonwoven fabric by applying paste-like binder liquids to the still unstable fibrous web, using a rotary screen printing machine (see, for example, Vliesstoffe, edited by W. Albrecht, H. Fuchs, and W. Kittelmann, Wiley-VCH (2000), Chapter 6.5, Chemical Methods, page 381). These methods have thus far not become established in the art due to the technical problem of uniformly binding a fibrous web using “adhesive” binders. The loose fibers of the fibrous web tend to adhere to the printing screen, and after a short time impede the printing process. This phenomenon may be counteracted by subjecting the fibrous web to intense compression or pressure (over the entire surface or at selected points), but the resulting products are therefore very flat and have less of a textile quality; in addition, the binder bleeds through heavily.
DE-A-29 14 617 describes a method for uniform, continuous imprinting of pastes onto the front and back sides of textile fabrics. According to the example, a fibrous web produced by carding is led through a calender and prebonded. A binder dispersion is then applied in a pattern to both sides of this textile fabric, using rollers, and drying is then performed to crosslink the binder.
Heretofore, nonwoven fabrics having heat-regulating properties have been produced by aftertreatment of nonwoven fabrics, i.e., bonded, mechanically stabilized textile surfaces, with heat-regulating materials. As a result of the prior bonding step, in many cases the elasticity and softness of these nonwoven fabrics leave much to be desired.